how to make a vector graphic disappear behind trees in my video layer?

I'm not sure if I worded that properly but I'm trying to make the vectored solstice script disappear behind the trees in the video when it pans down to the ground. Any one that can help me achieve this effect it would be appreciated. I thought it was going to be simple but I'm stuck on it right now, also i'm new to After Effects. thanks!

I'd duplicate the video layer, and apply the Threshold effect. You ought to get a good delineation between trees and sky. Add solids to make it white on black, precomp it and use it as a luma or luma inverted matte for the writing.

2 ) Comp the lettering over the background on the bottom layer .... this will give you lettering in front of the trees which might sound like I've missed the point but there is method here ...

2 ) Key the trees ( etc ) in the middle layer over the bottom layer using the top layer as a track matte - adjusting the luminance levels on the track matte using 'curves' to control the opacity and spread of the key.

The advantage of this method is that you can use it where its hard to get a good key and also in comps where you want to create subtle effects.

Sometimes with trees and its useful to have a bit of random transparency detail as it helps to give the idea that subject is traveling behind and that helps sell the shot.

If you want to try this its sometimes worth having a few copies of the keyed trees ( or whatever ) and set the levels differently to catch various parts of the image - for example you might want one key a bit 'soft' and transparent for blurry details out of focus leaves etc and another layer on top with a more general 'tighter' key possibly followed by another layer with a much harder 'crushed' black and white key to make sure main main branches trunk etc are good and solid without 'holes' in them.

This technique can be very useful if your subject is moving fast ( ish ) and the trees are a bit fuzzy and hard to key -- sometimes you can get away with loads using this method.....

I'm sure Daves technique will work just fine but this one is worth knowing for those awkward shots.